Format: ORAL

Catarina Branco1,2,3; Rúben Rego1,2,4; Gabriel Marais1,2,3; Raquel Linheiro1,2,3; Raquel Tavares1,2,3; Sylvain Santoni5; Hugo Tessarotto5; Jos Käfer6; Alessio Iannucci7,8; Claudio Ciofi7; Maria A. Diroma7; Chiara Natali7,9; Marco Morselli10; Guilherme Roxo1,2,4; Roberto Resendes1; Manuela Sim-Sim11,12,13; Helena Trindade11,13; Sara Vicente11,14; João P. Marques1,2; Vitor Sousa11,15; José Melo-Ferreira1,2,3; Ann M. Cartney16; Alice Mouton7,17; Giulio Formenti18; Mónica Moura1,2,3

1 Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Universidade do Porto, Vila do Conde, Portugal 2 BIOPOLIS Program in Genomics, Biodiversity and Land Planning, Vila do Conde, Portugal 3 Faculdade de Ciências, Universidade do Porto, Porto, Portugal 4 UNESCO Chair – Land Within Sea: Biodiversity & Sustainability in Atlantic Islands 5 Université de Montpellier, Montpelier, France 6 Université de Lyon, Université Lyon 1, Villeurbanne, France 7 University of Florence, Sesto Fiorentino, Italy 8 National Biodiversity Future Center (NBFC), Palermo, Italy 9 Okinawa Institute of Science and Technology, Okinawa, Japan 10 University of Parma, Parma, Italy 11 Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal 12 Museu Nacional de História Natural e da Ciência (MUHNAC), Universidade de Lisboa, Lisboa, Portugal 13 Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal 14 Escola Superior de Saúde Ribeiro Sanches (ERISA), Instituto Politécnico da Lusofonia (IPLUSO), Lisboa, Portugal 15 Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal 16 Genomics Institute, University of California, Santa Cruz, USA 17 University of Liege, Liege, Belgium 18 The Rockefeller University, New York City, USA

The Laurus genus exhibits a current distribution encompassing the southern Black Sea region, the Mediterranean Basin, Morocco, and the Macaronesian islands (i.e., the Azores, Madeira, and Canaries archipelagos). Despite numerous attempts, previous studies faced challenges in elucidating the taxonomy, ploidy, and phylogenetic relationships within this genus. Concerning the taxonomy, two species are traditionally recognized: L. nobilis and L. azorica. This study delves into L. azorica, a dioecious tree endemic to the Azores archipelago that falls within the European Reference Genome Atlas (ERGA) initiative to ensure high-quality reference genomes of the European biodiversity. Despite the well-established dioecy of this species, its sex-determination system remains elusive. Here, we aim (i) to obtain a chromosome-level assembly and (ii) to identify its sex determination system. Firstly, long-read sequencing data from Pacific Biosciences (PacBio) were acquired to ensure a robust genomic dataset. Additionally, chromatin conformation capture data (Hi-C) were incorporated to facilitate the construction of a chromosome-level assembly. Then, Illumina short reads for 32 individuals were obtained, ensuring an even representation of phenotypic males and females. SDPOP(Kfer et al. 2021) analysis will be applied to infer the genes sex-linkage by modelling populations allele and genotypic frequencies. This framework allows statistical testing of alternative sex-determination systems (i.e., presence or absence of sex chromosomes, distinguishing between XY and ZW systems). Our preliminary results suggest that L. azorica is tetraploid (n=18), consistent with prior studies on this genus. Ongoing research is expected to yield additional insights into the sex-determination system and contribute valuable information to broader studies on dioecy and sex-determination mechanisms in plant species. Moreover, this study serves as a cornerstone for further exploration into the evolutionary dynamics within the Laurus genus.